The present invention relates to a combined air shutter and insect guard for use in a gas appliance. The device is rotatably mounted around the mixing tube of a gas burner and controls the air intake of the mixing tube and also serves as an insect guard to prevent insects from entering and clogging the mixing tube.
The use of outdoor gas appliances such as gas grills and gas barbecues has become prevalent today. However, because of the use of these appliances and their storage in an outdoor location, the appliances are subject to the elements, which includes allowing insect life access to their internal components.
For instance, insects such as spiders, wasps, bees, grasshoppers, and arachnids have been known to enter the mixing tubes and other fuel feed lines of gas burners and clog theses lines thus interrupting fuel flow to the burners which may cause improper operation or malfunctioning of the unit. In addition, insects which enter the mixing tube may die inside the tube and their bodies may disrupt or constrict the flow of gas to the burner which is undesirable for proper operation of these grills.
Past gas grill manufacturers have attempted to remedy this problem by recommending periodic cleaning of the mixing tube and providing tools to perform this task. In addition manufacturers of gas grills have cautioned users about this type of problem and recommended periodic inspections of the mixing tube and primary air opening.
Additionally, the problem of insect intrusion into the mixing tube has been addressed in U.S. Pat. No. 4,747,391, entitled xe2x80x9cInsect Guard For A Gas Appliancexe2x80x9d. The guard includes a cylindrical member which slideably fits over the end of the mixing tube. The member is configured in the shape of a thimble and is made of screen material. The screen member extends circumfuentially around the mixing tube to encompass air openings on the outer periphery of the Venturi tube. The device serves only as an insect guard.
In a separate embodiment of the device disclosed in U.S. Pat. No. 4,747,391 a separate air shutter is disclosed. The air shutter controls (adjusts) the fuel to air mixture which reaches the burner. The air shutter can be rotated around the mixing tube to adjust the size of the primary air opening. A separate insect guard which is a screen is inserted into the mixing tube at the primary opening to restrict the air opening from entrance by an insect.
A U.S. Pat. No. 3,905,756 issued to William J. Ferlin, et al., on Sep. 16, 1975, is entitled xe2x80x9cShutter Structure And Mixing Tube Assembly For Gas Burnersxe2x80x9d The device controls the mixture of fuel gas and air that is furnished to a gas burner. In this patent a C-shaped band of metal is frictionally engaged around a portion of the mixing tube having a pair of opposed primary air inlets. The band of metal has one opening in the body portion thereof which is disposed for registry with one of the primary air inlets openings. A second opening is defined by the spacing between distal ends of the c-shaped member and is disposed registry with a primary air opening. This device does not provide means for preventing insect intrusion when a side primary opening of the mixing tube is open to the atmosphere.
In accordance to the present invention, there is provided a combined air shutter and insect guard for use in a gas appliance provided with a mixing tube having at least one primary air inlet therein. The insect guard portion of the combined air shutter and insect guard prevents clogging of the mixing tube by insects which may attempt to enter the primary air opening even while primary air is being admitted into the tube. Integral with and forming a portion of the combined air shutter and insect guard is a shutter portion which partially or completely blocks a primary inlet and thus controls the fuel to air mixture which reaches the burner.
It is, therefore, an object of the present invention to provide a combined insect guard and shutter device which guards against intrusion of insects into a primary air entrance of a mixing tube and which adjusts the fuel to air mixture in the mixing tube.